Method for state recovery during assist and restart in a decoder

Details Method for state recovery during assist and restart in a decoder Method for state recovery during assist and restart in a decoder

1994-03-01

1996-10-15

Beausoliel, Jr., Robert W.

39518213, 39518502, G06F 1100, G06F 1120

Patent

active

055662986

ABSTRACT:
A state recovery and restart method that simplifies assist handling. The recovery and restart method also handles micro-branch mispredictions. An assist sequence is executed in microcode to assist an error-causing macroinstruction. If data is required from an error-causing macroinstruction, it is fetched, decoded, and macro-alias registers are restored with macro-alias data. To recover the state of the micro-alias registers, micro-alias data from a micro-operation of the flow may be loaded into the micro-alias register. Subsequently, control returns to the Micro-operation Sequence (MS) unit to issue further error correction Control micro-operations (Cuops). In order to simplify restart, the Cuops originating from the error-causing macroinstruction supplied by the translate programmable logic arrays (XLAT PLAs) are loaded into the Cuop registers, with their valid bits unasserted. If microcode requests a restart beginning at one of the Cuops stored in the Cuop register, then the bits for that Cuop and subsequent Cuops are marked valid. Thus, the instruction can be restarted anywhere within the microcode sequence.

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